PREFACE. 



THIS collection of examples for illustrating the most 

 important processes for determining the composition 

 of mineral substances, is designed chiefly for use in 

 the laboratory. 



It is drawn up under the impression that it is easier 

 for most minds to obtain a clear insight into general 

 relations and laws by the study of special cases, than, 

 inversely, to acquire a knowledge of individual cases 

 by first directing the attention to general rules. An 

 endeavor has been made to arrange the book in such 

 a manner as still to leave enough to demand the re- 

 flection of the student and the explanations of the 

 teacher ; the latter also must point out the authority for 

 the individual methods here given, and also which he 

 considers the best. 



FRIEDKIOH WOHLER. 



